The Merivale Rail Bridge - Brisbane

The location of the bridge just upstream of another bridge and a 90° bend in the Brisbane River dictated a long span bridge to cater for the coral and coal barges of up to 5,000 tonnes weight using the river (Fig. 9). Maximum grading out of South Brisbane railway station cleared the river navigation clearance by only a small margin and this combination of long span and minimum construction depth dictated a shallow bridge deck supported from above. The designers looked at a wide range of possibilities and selected a shallow steel-framed deck structure suspended by inclined steel wire rope hangers from twin tied steel box arches. Lateral stiffness was enhanced by inclining the arches inwards to meet at their crown. The arch ribs and the horizontal ties joining the arch springings were fabricated by welding in segmental boxes using high ductility medium high strength steel and were field-jointed by high tensile steel bolts. The main span is 133 metres long and the deck is suspended from the arches by thirty-two 94.5 mm diameter steel rope bridge cables. The bridge was designed by consulting engineers, Cameron McNamara Pty. Ltd. and was fabricated and erected by Transfield (Qld.) Pty. Ltd. It was completed in 1979.